Is this what 'randomize' means?  I thought that at this level, it indicates a wrapper that randomly selects which of a number of child "problems" gets displayed (i.e. RandomizeModule).  There is a "rerandomize" option within a problem which *may* allow the values in a problem to change (depending on its setting), but I would have thought that for such problems the module_type would still be "problem".  Just asking -- I can't tell from the code.